Acute cerebellar ataxia is a condition that occurs in previously healthy children, typically following an infectious process. It is most common in children younger than 6 years, but cases have been reported in adolescents. While the etiology is unknown, it is thought to be a postinfectious autoimmune process, with varicella accounting for 25% of cases. Other infections include human herpesvirus 6, measles, coxsackievirus, Epstein-Barr virus (EBV), enteroviruses, mumps, parvovirus B19, Lyme disease, Mycoplasma pneumoniae, and malaria. Acute cerebellar ataxia may follow vaccination, but this is rare compared with active infection.

Patients typically present with rapid development of symptoms over the course of a few hours, with gait disturbance being the most common symptom. Other symptoms include fine motor control problems, tremor, nystagmus, slurred speech, dysarthria, and vomiting. Fever, meningismus, and seizures are absent. Physical examination reveals a wide-based staggering gait, speech abnormalities with fluctuation in rhythm and tone, and impaired coordination as demonstrated by over / under shooting on finger-to-nose testing and difficulty with rapid alternating movements.

Prognosis is good as most children have complete resolution of symptoms within 2-3 weeks of presentation.